fix: ensure there is always a free thread for non-worker scripts

Author: dunglas

frankenphp.c

@@ -558,9 +558,8 @@ static void *manager_thread(void *arg) {
 	free(arg);
 
 	uintptr_t rh;
-	while ((rh = go_fetch_request())) {
+	while ((rh = go_fetch_request()))
 		thpool_add_work(thpool, go_execute_script, (void *) rh);
-	}
 
 	/* channel closed, shutdown gracefully */
 	thpool_wait(thpool);

frankenphp.go

@@ -5,8 +5,9 @@
 // [FrankenPHP app server]: https://frankenphp.dev
 package frankenphp
 
+//go:generate  rm -Rf C-Thread-Pool/
 //go:generate git clone --branch=feat/mac-os-compat --depth=1 git@github.com:dunglas/C-Thread-Pool.git
-//go:generate rm -rf C-Thread-Pool/.git C-Thread-Pool/.circleci C-Thread-Pool/docs C-Thread-Pool/tests
+//go:generate rm -Rf C-Thread-Pool/.git C-Thread-Pool/.circleci C-Thread-Pool/docs C-Thread-Pool/tests
 
 // #cgo CFLAGS: -Wall
 // #cgo CFLAGS: -I/usr/local/include/php -I/usr/local/include/php/Zend -I/usr/local/include/php/TSRM -I/usr/local/include/php/main
@@ -45,6 +46,7 @@ var (
 	AlreaydStartedError         = errors.New("FrankenPHP is already started")
 	InvalidPHPVersionError      = errors.New("FrankenPHP is only compatible with PHP 8.2+")
 	ZendSignalsError            = errors.New("Zend Signals are enabled, recompile PHP with --disable-zend-signals")
+	NotEnoughThreads            = errors.New("the number of threads must be superior to the number of workers")
 	MainThreadCreationError     = errors.New("error creating the main thread")
 	RequestContextCreationError = errors.New("error during request context creation")
 	RequestStartupError         = errors.New("error during PHP request startup")
@@ -221,16 +223,18 @@ func Init(options ...Option) error {
 			opt.workers[i].num = numCPU
 		}
 
-		numWorkers += w.num
+		numWorkers += opt.workers[i].num
 	}
 
 	if opt.numThreads <= 0 {
 		if numWorkers >= numCPU {
-			// Keep a free thread to handle requests not handled by a worker
-			opt.numThreads = numCPU + 1
+			// Start at least as many threads as workers, and keep a free thread to handle requests in non-worker mode
+			opt.numThreads = numWorkers + 1
 		} else {
 			opt.numThreads = numCPU
 		}
+	} else if opt.numThreads <= numWorkers {
+		return NotEnoughThreads
 	}
 
 	switch C.frankenphp_check_version() {

frankenphp_test.go

@@ -39,9 +39,6 @@ func runTest(t *testing.T, test func(func(http.ResponseWriter, *http.Request), *
 	if opts == nil {
 		opts = &testOptions{}
 	}
-	if opts.nbWorkers == 0 {
-		opts.nbWorkers = 2
-	}
 	if opts.nbParrallelRequests == 0 {
 		opts.nbParrallelRequests = 100
 	}

testdata/Caddyfile

@@ -1,7 +1,7 @@
 {
 	debug
 	frankenphp {
-		#worker ./phpinfo.php
+		worker ./phpinfo.php
 	}
 }
 

worker_test.go

@@ -49,6 +49,19 @@ func TestWorkerDie(t *testing.T) {
 	}, &testOptions{workerScript: "die.php", nbWorkers: 1, nbParrallelRequests: 10})
 }
 
+func TestNonWorkerModeAlwaysWorks(t *testing.T) {
+	runTest(t, func(handler func(http.ResponseWriter, *http.Request), _ *httptest.Server, i int) {
+		req := httptest.NewRequest("GET", "http://example.com/index.php", nil)
+		w := httptest.NewRecorder()
+		handler(w, req)
+
+		resp := w.Result()
+		body, _ := io.ReadAll(resp.Body)
+
+		assert.Contains(t, string(body), "I am by birth a Genevese")
+	}, &testOptions{workerScript: "phpinfo.php"})
+}
+
 func ExampleServeHTTP_workers() {
 	if err := frankenphp.Init(
 		frankenphp.WithWorkers("worker1.php", 4),